The present invention relates to processing an omnidirectional video frame, and more particularly, to a method and an apparatus for generating a projection-based frame with a 360-degree image content represented by triangular projection faces assembled in an octahedron projection (OHP) layout.
Virtual reality (VR) with head-mounted displays (HMDs) is associated with a variety of applications. The ability to show wide field of view content to a user can be used to provide immersive visual experiences. A real-world environment has to be captured in all directions resulting in an omnidirectional video corresponding to a viewing sphere. With advances in camera rigs and HMDs, the delivery of VR content may soon become the bottleneck due to the high bitrate required for representing such a 360-degree image content. When the resolution of the omnidirectional video is 4K or higher, data compression/encoding is critical to bitrate reduction.
In general, the omnidirectional video corresponding to a viewing sphere is transformed into a projection-based frame with a 360-degree image content represented by projection faces arranged in a 360-degree Virtual Reality (360 VR) projection layout, and then the projection-based frame is encoded into a bitstream for transmission. However, if the employed 360 VR projection layout is not properly designed, it is possible that the projection-based frame has many image content discontinuity boundaries resulting from assembling of the projection faces. The encoding/decoding quality may be degraded due to the image content discontinuity boundaries.